The Hidden Depths of Planetary Atmospheres
The Hidden Depths of Planetary Atmospheres
复制标题
行星大气层的隐藏深处
DOI：
10.3847/1538-4357/aad80f
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
M. Swain
中科院分区：
文献类型：
--
作者：
Yan B'etr'emieux;M. Swain
折光边界以下的大气区域隐藏在翼面观测中。因此，折射在地球的透射光谱中产生了一个灰色连续体，它可以隐藏与大气不透明源相关的光谱特征。我们将折射理论与描述表面和云对透射光谱影响的最新分析进展相结合，以表达原子和分子消光以及碰撞诱导吸收在大气不透明空间中的边界位置。这使得人们可以快速估计折射如何影响混合良好的大气中的光谱特征。我们发现，太阳系行星和系外行星在边缘观测的几何形状上的差异导致了这一边界的不同位置，并且与太阳系冷气体巨星的观测相比，系外行星凌日中隐藏了超过4个额外的大气尺度高度。我们探索了在混合良好的等温大气中，系外行星凌日的折射边界位置如何随其温度和组成、行星主恒星的光谱类型和行星的大小而变化。我们证明，与氦气大气相比，在具有CO2大气的类地行星中隐藏了五个额外的尺度高度，导致光谱比单独的较小尺度高度更平坦。我们提供了一些系外行星的结果，特别是那些在TRAPPIST-1系统中的行星，以帮助科学界在没有辐射传输计算的情况下估计折射对光谱特征大小的影响，从而帮助完善詹姆斯网络太空望远镜的观测计划。
Atmospheric regions below a refractive boundary are hidden in limb observations. Refraction thus creates a gray continuum in the planet’s transmission spectrum, which can hide spectral features associated with sources of atmospheric opacity. We combine refractive theory with recent analytical advances describing the effects of surfaces and clouds on transmission spectra, to express the location of this boundary in atmospheric opacity space, for both atomic and molecular extinction, as well as collision-induced absorption. This allows one to quickly estimate how refraction affects spectral features in well-mixed atmospheres. We show that differences in the geometry of limb observations between solar system planets and exoplanets lead to different locations of this boundary, and that more than four extra scale heights of atmosphere are hidden in exoplanet transits compared to solar system observations of cold gas giants. We explore how the location of this refractive boundary in exoplanet transits changes in a well-mixed isothermal atmosphere with its temperature and composition, the spectral type of the planet’s host star, and the size of the planet. We demonstrate that five extra scale heights of atmosphere are hidden in a terrestrial planet with a CO2 atmosphere compared to a helium atmosphere, resulting in a flatter spectrum than from its smaller scale height alone. We provide results for a few exoplanets, notably those in the TRAPPIST-1 system, to help the scientific community estimate the impact of refraction on the size of spectral features without radiative transfer calculations, and thus help refine planned James Web Space Telescope observations.
影响因子：
4.8
作者：
J. Bento;P. Wheatley;C. Copperwheat;J. Fortney;V. Dhillon;R. Hickman;S. Littlefair;T. Marsh;S. Parsons;J. Southworth
通讯作者：
J. Bento;P. Wheatley;C. Copperwheat;J. Fortney;V. Dhillon;R. Hickman;S. Littlefair;T. Marsh;S. Parsons;J. Southworth
影响因子：
4.8
作者：
R. MacDonald;N. Madhusudhan
通讯作者：
R. MacDonald;N. Madhusudhan
影响因子：
1.4
作者：
J. Tennyson;S. Yurchenko;A. Al-Refaie;Victoria H J Clark;K. Chubb;E. Conway;Akhil Dewan;Maire N Gorman;C. Hill;A. Lynas-Gray;Thomas M. Mellor;Laura K. McKemmish;A. Owens;O. Polyansky;M. Semenov;W. Somogyi;G. Tinetti;Apoorva Upadhyay;I. Waldmann;Yixin Wang;Samuel Wright;O. Yurchenko
通讯作者：
J. Tennyson;S. Yurchenko;A. Al-Refaie;Victoria H J Clark;K. Chubb;E. Conway;Akhil Dewan;Maire N Gorman;C. Hill;A. Lynas-Gray;Thomas M. Mellor;Laura K. McKemmish;A. Owens;O. Polyansky;M. Semenov;W. Somogyi;G. Tinetti;Apoorva Upadhyay;I. Waldmann;Yixin Wang;Samuel Wright;O. Yurchenko